1. Technical Field
The present invention relates to manufacturing method for a gallium nitride (GaN)-based semiconductor device and a semiconductor device.
2. Related Art
Dry-etching of a GaN-based semiconductor can employ ICP-RIE (inductively coupled plasma reactive-ion etching) using a chlorine-based gas, as shown in Non-Patent Document 1, for example.    Non-Patent Document 1: Technical Report of the IEICE, 2009, ED. 2009-43
However, the electron temperature is high in inductively coupled plasma. With ICP-RIE, high-energy ions collide with the semiconductor, thereby causing the etching surface to be uneven and damaging the semiconductor, which results in a decrease in the electrical characteristics of the semiconductor device. Furthermore, when etching a GaN-based semiconductor, if a chlorine-based gas such as chlorine (Cl2) or boron trichloride (BCl3) is used as the etching gas, chlorides and the like are formed in the surface, and therefore chlorine remains in the etched surface. This residual chlorine acts as an impurity, and therefore the resulting GaN-based semiconductor device has impaired carrier flow, which causes a reduction in the electrical characteristics.
Therefore, it is an object of an aspect of the innovations herein to provide a manufacturing method for a GaN-based semiconductor device and a semiconductor device, which is capable of overcoming the above drawbacks accompanying the related art. The above and other objects can be achieved by combinations described in the claims.